The present invention is generally related to the field of building systems. More particularly, the present invention is directed to building toys, and even more specifically to building toys where a child can construct, and then play on, the resulting structures. Alternatively, the invention could be used for other structures such as a compost bin, or a dog or horse training apparatus, etc. The present invention comprises a plurality of interlocking planks and posts which may be assembled in a multitude of potential configurations.